Auto merge of #148167 - Zalathar:rollup-njf167h, r=Zalathar

Rollup of 4 pull requests

Successful merges:

 - #145939 (const `select_unpredictable`)
 - #147478 (More intuitive error when using self to instantiate tuple struct with private field)
 - #147866 (Add built-in `const` impls for `Clone` and `Copy`)
 - #148153 (Fix duplicate 'the the' typos in comments)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_hir_typeck/src/writeback.rs

@@ -798,7 +798,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
                 } else {
                     let predicate = self.tcx().erase_and_anonymize_regions(predicate);
                     if cause.has_infer() || cause.has_placeholders() {
-                        // We can't use the the obligation cause as it references
+                        // We can't use the obligation cause as it references
                         // information local to this query.
                         cause = self.fcx.misc(cause.span);
                     }

compiler/rustc_next_trait_solver/src/solve/effect_goals.rs

@@ -211,10 +211,32 @@ where
     }
 
     fn consider_builtin_copy_clone_candidate(
-        _ecx: &mut EvalCtxt<'_, D>,
-        _goal: Goal<I, Self>,
+        ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
     ) -> Result<Candidate<I>, NoSolution> {
-        Err(NoSolution)
+        let cx = ecx.cx();
+
+        let self_ty = goal.predicate.self_ty();
+        let constituent_tys =
+            structural_traits::instantiate_constituent_tys_for_copy_clone_trait(ecx, self_ty)?;
+
+        ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
+            ecx.enter_forall(constituent_tys, |ecx, tys| {
+                ecx.add_goals(
+                    GoalSource::ImplWhereBound,
+                    tys.into_iter().map(|ty| {
+                        goal.with(
+                            cx,
+                            ty::ClauseKind::HostEffect(
+                                goal.predicate.with_replaced_self_ty(cx, ty),
+                            ),
+                        )
+                    }),
+                );
+            });
+
+            ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+        })
     }
 
     fn consider_builtin_fn_ptr_trait_candidate(

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -180,6 +180,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
         let mut expected = source.descr_expected();
         let path_str = Segment::names_to_string(path);
         let item_str = path.last().unwrap().ident;
+
         if let Some(res) = res {
             BaseError {
                 msg: format!("expected {}, found {} `{}`", expected, res.descr(), path_str),
@@ -821,12 +822,18 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     args_snippet = snippet;
                 }
 
-                err.span_suggestion(
-                    call_span,
-                    format!("try calling `{ident}` as a method"),
-                    format!("self.{path_str}({args_snippet})"),
-                    Applicability::MachineApplicable,
-                );
+                if let Some(Res::Def(DefKind::Struct, def_id)) = res {
+                    self.update_err_for_private_tuple_struct_fields(err, &source, def_id);
+                    err.note("constructor is not visible here due to private fields");
+                } else {
+                    err.span_suggestion(
+                        call_span,
+                        format!("try calling `{ident}` as a method"),
+                        format!("self.{path_str}({args_snippet})"),
+                        Applicability::MachineApplicable,
+                    );
+                }
+
                 return (true, suggested_candidates, candidates);
             }
         }
@@ -1611,6 +1618,47 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
         }
     }
 
+    fn update_err_for_private_tuple_struct_fields(
+        &mut self,
+        err: &mut Diag<'_>,
+        source: &PathSource<'_, '_, '_>,
+        def_id: DefId,
+    ) -> Option<Vec<Span>> {
+        match source {
+            // e.g. `if let Enum::TupleVariant(field1, field2) = _`
+            PathSource::TupleStruct(_, pattern_spans) => {
+                err.primary_message(
+                    "cannot match against a tuple struct which contains private fields",
+                );
+
+                // Use spans of the tuple struct pattern.
+                Some(Vec::from(*pattern_spans))
+            }
+            // e.g. `let _ = Enum::TupleVariant(field1, field2);`
+            PathSource::Expr(Some(Expr {
+                kind: ExprKind::Call(path, args),
+                span: call_span,
+                ..
+            })) => {
+                err.primary_message(
+                    "cannot initialize a tuple struct which contains private fields",
+                );
+                self.suggest_alternative_construction_methods(
+                    def_id,
+                    err,
+                    path.span,
+                    *call_span,
+                    &args[..],
+                );
+                // Use spans of the tuple struct definition.
+                self.r
+                    .field_idents(def_id)
+                    .map(|fields| fields.iter().map(|f| f.span).collect::<Vec<_>>())
+            }
+            _ => None,
+        }
+    }
+
     /// Provides context-dependent help for errors reported by the `smart_resolve_path_fragment`
     /// function.
     /// Returns `true` if able to provide context-dependent help.
@@ -1942,42 +1990,6 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     return true;
                 };
 
-                let update_message =
-                    |this: &mut Self, err: &mut Diag<'_>, source: &PathSource<'_, '_, '_>| {
-                        match source {
-                            // e.g. `if let Enum::TupleVariant(field1, field2) = _`
-                            PathSource::TupleStruct(_, pattern_spans) => {
-                                err.primary_message(
-                                "cannot match against a tuple struct which contains private fields",
-                            );
-
-                                // Use spans of the tuple struct pattern.
-                                Some(Vec::from(*pattern_spans))
-                            }
-                            // e.g. `let _ = Enum::TupleVariant(field1, field2);`
-                            PathSource::Expr(Some(Expr {
-                                kind: ExprKind::Call(path, args),
-                                span: call_span,
-                                ..
-                            })) => {
-                                err.primary_message(
-                                "cannot initialize a tuple struct which contains private fields",
-                            );
-                                this.suggest_alternative_construction_methods(
-                                    def_id,
-                                    err,
-                                    path.span,
-                                    *call_span,
-                                    &args[..],
-                                );
-                                // Use spans of the tuple struct definition.
-                                this.r
-                                    .field_idents(def_id)
-                                    .map(|fields| fields.iter().map(|f| f.span).collect::<Vec<_>>())
-                            }
-                            _ => None,
-                        }
-                    };
                 let is_accessible = self.r.is_accessible_from(ctor_vis, self.parent_scope.module);
                 if let Some(use_span) = self.r.inaccessible_ctor_reexport.get(&span)
                     && is_accessible
@@ -2006,13 +2018,14 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                             Applicability::MachineApplicable,
                         );
                     }
-                    update_message(self, err, &source);
+                    self.update_err_for_private_tuple_struct_fields(err, &source, def_id);
                 }
                 if !is_expected(ctor_def) || is_accessible {
                     return true;
                 }
 
-                let field_spans = update_message(self, err, &source);
+                let field_spans =
+                    self.update_err_for_private_tuple_struct_fields(err, &source, def_id);
 
                 if let Some(spans) =
                     field_spans.filter(|spans| spans.len() > 0 && fields.len() == spans.len())

compiler/rustc_trait_selection/src/traits/effects.rs

@@ -8,7 +8,7 @@ use rustc_middle::span_bug;
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::elaborate::elaborate;
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
-use rustc_middle::ty::{self, TypingMode};
+use rustc_middle::ty::{self, Ty, TypingMode};
 use thin_vec::{ThinVec, thin_vec};
 
 use super::SelectionContext;
@@ -303,6 +303,9 @@ fn evaluate_host_effect_from_builtin_impls<'tcx>(
     obligation: &HostEffectObligation<'tcx>,
 ) -> Result<ThinVec<PredicateObligation<'tcx>>, EvaluationFailure> {
     match selcx.tcx().as_lang_item(obligation.predicate.def_id()) {
+        Some(LangItem::Copy | LangItem::Clone) => {
+            evaluate_host_effect_for_copy_clone_goal(selcx, obligation)
+        }
         Some(LangItem::Destruct) => evaluate_host_effect_for_destruct_goal(selcx, obligation),
         Some(LangItem::Fn | LangItem::FnMut | LangItem::FnOnce) => {
             evaluate_host_effect_for_fn_goal(selcx, obligation)
@@ -311,6 +314,100 @@ fn evaluate_host_effect_from_builtin_impls<'tcx>(
     }
 }
 
+fn evaluate_host_effect_for_copy_clone_goal<'tcx>(
+    selcx: &mut SelectionContext<'_, 'tcx>,
+    obligation: &HostEffectObligation<'tcx>,
+) -> Result<ThinVec<PredicateObligation<'tcx>>, EvaluationFailure> {
+    let tcx = selcx.tcx();
+    let self_ty = obligation.predicate.self_ty();
+    let constituent_tys = match *self_ty.kind() {
+        // impl Copy/Clone for FnDef, FnPtr
+        ty::FnDef(..) | ty::FnPtr(..) | ty::Error(_) => Ok(ty::Binder::dummy(vec![])),
+
+        // Implementations are provided in core
+        ty::Uint(_)
+        | ty::Int(_)
+        | ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
+        | ty::Bool
+        | ty::Float(_)
+        | ty::Char
+        | ty::RawPtr(..)
+        | ty::Never
+        | ty::Ref(_, _, ty::Mutability::Not)
+        | ty::Array(..) => Err(EvaluationFailure::NoSolution),
+
+        // Cannot implement in core, as we can't be generic over patterns yet,
+        // so we'd have to list all patterns and type combinations.
+        ty::Pat(ty, ..) => Ok(ty::Binder::dummy(vec![ty])),
+
+        ty::Dynamic(..)
+        | ty::Str
+        | ty::Slice(_)
+        | ty::Foreign(..)
+        | ty::Ref(_, _, ty::Mutability::Mut)
+        | ty::Adt(_, _)
+        | ty::Alias(_, _)
+        | ty::Param(_)
+        | ty::Placeholder(..) => Err(EvaluationFailure::NoSolution),
+
+        ty::Bound(..)
+        | ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
+            panic!("unexpected type `{self_ty:?}`")
+        }
+
+        // impl Copy/Clone for (T1, T2, .., Tn) where T1: Copy/Clone, T2: Copy/Clone, .. Tn: Copy/Clone
+        ty::Tuple(tys) => Ok(ty::Binder::dummy(tys.to_vec())),
+
+        // impl Copy/Clone for Closure where Self::TupledUpvars: Copy/Clone
+        ty::Closure(_, args) => Ok(ty::Binder::dummy(vec![args.as_closure().tupled_upvars_ty()])),
+
+        // impl Copy/Clone for CoroutineClosure where Self::TupledUpvars: Copy/Clone
+        ty::CoroutineClosure(_, args) => {
+            Ok(ty::Binder::dummy(vec![args.as_coroutine_closure().tupled_upvars_ty()]))
+        }
+
+        // only when `coroutine_clone` is enabled and the coroutine is movable
+        // impl Copy/Clone for Coroutine where T: Copy/Clone forall T in (upvars, witnesses)
+        ty::Coroutine(def_id, args) => {
+            if selcx.should_stall_coroutine(def_id) {
+                return Err(EvaluationFailure::Ambiguous);
+            }
+            match tcx.coroutine_movability(def_id) {
+                ty::Movability::Static => Err(EvaluationFailure::NoSolution),
+                ty::Movability::Movable => {
+                    if tcx.features().coroutine_clone() {
+                        Ok(ty::Binder::dummy(vec![
+                            args.as_coroutine().tupled_upvars_ty(),
+                            Ty::new_coroutine_witness_for_coroutine(tcx, def_id, args),
+                        ]))
+                    } else {
+                        Err(EvaluationFailure::NoSolution)
+                    }
+                }
+            }
+        }
+
+        ty::UnsafeBinder(_) => Err(EvaluationFailure::NoSolution),
+
+        // impl Copy/Clone for CoroutineWitness where T: Copy/Clone forall T in coroutine_hidden_types
+        ty::CoroutineWitness(def_id, args) => Ok(tcx
+            .coroutine_hidden_types(def_id)
+            .instantiate(tcx, args)
+            .map_bound(|bound| bound.types.to_vec())),
+    }?;
+
+    Ok(constituent_tys
+        .iter()
+        .map(|ty| {
+            obligation.with(
+                tcx,
+                ty.map_bound(|ty| ty::TraitRef::new(tcx, obligation.predicate.def_id(), [ty]))
+                    .to_host_effect_clause(tcx, obligation.predicate.constness),
+            )
+        })
+        .collect())
+}
+
 // NOTE: Keep this in sync with `const_conditions_for_destruct` in the new solver.
 fn evaluate_host_effect_for_destruct_goal<'tcx>(
     selcx: &mut SelectionContext<'_, 'tcx>,

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -2877,7 +2877,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         obligations
     }
 
-    fn should_stall_coroutine(&self, def_id: DefId) -> bool {
+    pub(super) fn should_stall_coroutine(&self, def_id: DefId) -> bool {
         match self.infcx.typing_mode() {
             TypingMode::Analysis { defining_opaque_types_and_generators: stalled_generators } => {
                 def_id.as_local().is_some_and(|def_id| stalled_generators.contains(&def_id))

compiler/rustc_type_ir/src/search_graph/mod.rs

@@ -924,7 +924,7 @@ enum RebaseReason<X: Cx> {
     ///
     /// This either happens in the first evaluation step for the cycle head.
     /// In this case the used provisional result depends on the cycle `PathKind`.
-    /// We store this path kind to check whether the the provisional cache entry
+    /// We store this path kind to check whether the provisional cache entry
     /// we're rebasing relied on the same cycles.
     ///
     /// In later iterations cycles always return `stack_entry.provisional_result`

library/core/src/hint.rs

@@ -4,6 +4,7 @@
 //!
 //! Hints may be compile time or runtime.
 
+use crate::marker::Destruct;
 use crate::mem::MaybeUninit;
 use crate::{intrinsics, ub_checks};
 
@@ -771,7 +772,11 @@ pub const fn cold_path() {
 /// ```
 #[inline(always)]
 #[stable(feature = "select_unpredictable", since = "1.88.0")]
-pub fn select_unpredictable<T>(condition: bool, true_val: T, false_val: T) -> T {
+#[rustc_const_unstable(feature = "const_select_unpredictable", issue = "145938")]
+pub const fn select_unpredictable<T>(condition: bool, true_val: T, false_val: T) -> T
+where
+    T: [const] Destruct,
+{
     // FIXME(https://github.com/rust-lang/unsafe-code-guidelines/issues/245):
     // Change this to use ManuallyDrop instead.
     let mut true_val = MaybeUninit::new(true_val);

library/core/src/intrinsics/mod.rs

@@ -55,7 +55,7 @@
 #![allow(missing_docs)]
 
 use crate::ffi::va_list::{VaArgSafe, VaListImpl};
-use crate::marker::{ConstParamTy, DiscriminantKind, PointeeSized, Tuple};
+use crate::marker::{ConstParamTy, Destruct, DiscriminantKind, PointeeSized, Tuple};
 use crate::ptr;
 
 mod bounds;
@@ -477,11 +477,15 @@ pub const fn unlikely(b: bool) -> bool {
 /// However unlike the public form, the intrinsic will not drop the value that
 /// is not selected.
 #[unstable(feature = "core_intrinsics", issue = "none")]
+#[rustc_const_unstable(feature = "const_select_unpredictable", issue = "145938")]
 #[rustc_intrinsic]
 #[rustc_nounwind]
 #[miri::intrinsic_fallback_is_spec]
 #[inline]
-pub fn select_unpredictable<T>(b: bool, true_val: T, false_val: T) -> T {
+pub const fn select_unpredictable<T>(b: bool, true_val: T, false_val: T) -> T
+where
+    T: [const] Destruct,
+{
     if b { true_val } else { false_val }
 }
 

library/core/src/lib.rs

@@ -106,6 +106,7 @@
 #![feature(const_cmp)]
 #![feature(const_destruct)]
 #![feature(const_eval_select)]
+#![feature(const_select_unpredictable)]
 #![feature(core_intrinsics)]
 #![feature(coverage_attribute)]
 #![feature(disjoint_bitor)]